How about betting against your favourite team, so when your fav team win, you happy even you lose your money and if your fav lose, you are also okay because you got money from the betting. So it's a win win for you.
Thats called arbitrage betting and you are not the first one to think of it in order to make money. Some bookies actually ban people who try to arbitrage but you can do that making the two bets on two different bookmakers who have almost similar odds. So you can probably understand that this would need a lot of research on which bookie has what odds and which bookies does not like people who arbitrage and so on.
As they say, always bet against the public, sometimes it work but you cannot use this strategy all the time as you will still loss in the long run.
Thats not always true. What will be the outcome of the game can be predicted by analysis but in the end it will only depend on your luck.
The bookies are already aware of our theory, so they adjust because they are smarter than us.
Correct but match fixing is also a factor.